The ignition of an internal combustion engine is a complex process involving the combination of many factors such as adequate cranking speeds, sufficient ignition energy, and the provision of an energetically combustible fuel/air mixture into the cylinder. During normal operation, both compression ignition (diesel) engines and spark ignition (gasoline) engines operate adequately on fuel delivered in near aerosol form. However, during the starting process in cold temperature environments, it has been generally found necessary to add volatile organic compounds (VOC) to fuel in order to provide combustible vapors for ignition. The principal engine ignition enhancing ingredient has been butane which has been blended into gasoline at refineries in anticipation of predicted weather conditions. These concentrations vary between summer and winter mixtures. That is, during the summer, a lower amount of butane is added to the gasoline and a higher amount is added during the winter.
The VOCs evaporating from gasoline are considered to be a contributor to smog. The EPA is preparing to limit the Reid vapor pressure of gasoline to meet more stringent VOC emission guidelines. Engines could become very difficult to start in cold weather as a result.
Prior methods have been devised in view of the aforementioned problem. The assignee of the present invention has developed a cylinder head recessed portion having a coating thereon comprising a thin film of synthetic resin which is thermally stable under the usual operating temperatures of the engine for controlling hydrocarbon emission. The U.S. Pat. No. 2,175,743 to Coffman, issued Oct. 10, 1939, discloses an auxiliary fuel tank system which under abnormal weather conditions supplies a liquid starting enhancer (butane or butane-containing gasoline) to a priming pump in response to operation of the starter of the engine. The U.S. Pat. Nos. 3,416,507 to Little, issued Dec. 17, 1968 and U.S. Pat. No. 4,346,683 to Burke, issued Aug. 31, 1982, both disclose supplementary fuel systems for enhancing low temperature operation. Both patents deal with an aerosol system. Hence, the aforementioned prior art patents all deal broadly with enhancer delivery during engine cranking.
The present invention provides an improvement over the prior art by providing means for injecting volatile components, such as fluids, into the intake manifold during starting/warm-up only and eliminating the need to have wasteful amounts of butane in the gasoline. The volatile components emitted from the fuel tank and carburetor are greatly reduced and it may be possible to eliminate the bulky activated carbon canisters now used to trap such losses. This invention could be used on diesel engines as well as gasoline engines. Further, any internal combustion engine starting process could benefit from the present invention, including aircraft reciprocating and turbine engines. The technology is particularly appropriate for emergency start equipment.